Help All calls made and received are Unknown

[lawman]

Everytime i make a phone call, when i go back into my recent calls it says "Unknown" as the number. Also when receiving any calls it comes up as "Unknown" even if i call off of my house phone and make sure its not a withheld number. Anyone know if this is a setting i have somehow activated or if there is something wrong with my phone?

Im on Vodafone and live in the UK.

Thank you!